= Trac Logging =
[[TracGuideToc]]
Trac supports logging of system messages using the standard [http://docs.python.org/lib/module-logging.html logging module] that comes with Python.
Logging is configured in the `[logging]` section in [wiki:TracIni#logging-section trac.ini].
== Supported Logging Methods ==
The log method is set using the `log_type` option in [wiki:TracIni#logging-section trac.ini], which takes any of the following values:
'''none'':: Suppress all log messages.
'''file''':: Log messages to a file, specified with the `log_file` option in [wiki:TracIni#logging-section trac.ini].
'''stderr''':: Output all log entries to console ([wiki:TracStandalone tracd] only).
'''syslog''':: (UNIX) Send all log messages to the local syslogd via named pipe `/dev/log`. By default, syslog will write them to the file /var/log/messages.
'''eventlog''':: (Windows) Use the system's NT Event Log for Trac logging.
== Log Levels ==
The verbosity level of logged messages can be set using the `log_level` option in [wiki:TracIni#logging-section trac.ini]. The log level defines the minimum level of urgency required for a message to be logged, and those levels are:
'''CRITICAL''':: Log only the most critical (typically fatal) errors.
'''ERROR''':: Log failures, bugs and errors.
'''WARN''':: Log warnings, non-interrupting events.
'''INFO''':: Diagnostic information, log information about all processing.
'''DEBUG''':: Trace messages, profiling, etc.
== Log Format ==
Starting with Trac 0.10.4 (see #2844), it is possible to set the output format for log entries. This can be done through the `log_format` option in [wiki:TracIni#logging-section trac.ini]. The format is a string which can contain any of the [http://docs.python.org/lib/node422.html Python logging Formatter variables]. Additonally, the following Trac-specific variables can be used:
'''$(basename)s''':: The last path component of the current environment.
'''$(path)s''':: The absolute path for the current environment.
'''$(project)s''':: The originating project's name.
Note that variables are identified using a dollar sign (`$(...)s`) instead of percent sign (`%(...)s`).
The default format is:
{{{
log_format = Trac[$(module)s] $(levelname)s: $(message)s
}}}
In a multi-project environment where all logs are sent to the same place (e.g. `syslog`), it makes sense to add the project name. In this example we use `basename` since that can generally be used to identify a project:
{{{
log_format = Trac[$(basename)s:$(module)s] $(levelname)s: $(message)s
}}}
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See also: TracIni, TracGuide, TracEnvironment